The camera is one of the most

相機是Unity最重要的元件之一

essential components in Unity.

相機將場景的內容呈現給使用者

The camera takes the contents of our scene

每個場景至少要一台相機來著色場景物件 不然甚麼都秀不出來

and displays it to our users.

當建立一個新場景時 同時也會產生一台相機

Every scene must have at least

這台相機叫主相機(Main camera)

one camera to render out scene objects

遊戲相機是建立在物件裡的元件

otherwise we have nothing to show.

代表我們可以像操縱其他物件一樣操縱它 給予結構、腳本控制或物理

When a new scene is created

要建立第一或第三人稱相機或橫向捲軸 我們可以讓Player物件成為相機的父物件

one game object is always created.

將相機調整到角色眼睛的高度 並往前看可以模擬第一人稱

This is the main camera.

將相機調整到角色的後上方來模擬第三人稱

The game view camera is a

要呈現益智遊戲或俯視射擊遊戲 相機應該是靜止並對著遊戲場景

component attached to a game object.

在範例裡，我們將相機置中 並移除任何不需要的旋轉數值

This means we can manipulate, or move our camera

讓鏡頭由上往下看並抬高點 模擬一個俯視射擊遊戲場景

like any other game object,

這裡我們用正射模式(Orthographic) 後面會解釋這個模式

including parenting, scripting,

一個場景裡可以有很多台相機 每台相機負責著色不同的環境區塊

or physical interaction.

本範例我們有三個相機

To create a first or third person camera,

第一台著色場景的動態物件，第二台 著色靜態背景第三台著色使用者介面

including side scrollers,

三台相機結合在一起就可以 呈現一個完整畫面給玩家

we can use the player object as the parent.

待會我們會討論如何一次使用三台相機

For first person cameras, make sure the camera

當在階層裡點選相機時會看到預覽畫面

is at the character's eye height

當場景有複數相機時我們可以 透過預覽來了解不同相機的內容

looking forward from the character's point of view.

全螢幕編輯時預覽的好處更明顯 就算場景裡只有一台相機

For a third person view, make sure the camera is

相機會呈現它看到的所有東西

above and behind the character.

呈現多少取決於相機前的白色框體

For a simple puzzle game or top-down shooter

這個叫做視錐

the camera would be static, simply

視錐像削去頂部的金字塔或錐體

looking at and rendering the game.

最頂端叫近視切面(Near Clipping Plane) 最底端叫遠視切面(Far Clipping Plane)

In this example we are going to centre the camera,

近端和遠端視切面控制相機的繪製距離

remove any unwanted rotation,

物件必須在遠端和近端中間才會被呈現

point it straight down and lift it above

四邊代表上下左右的可視範圍

the game board to simulate a top-down game.

任何在錐體裡的場景會被著色

In this case we are using the orthographic

相機有透視模式(Perspective) 和正射模式(Orthographic)兩種模式

mode on the camera, which we will cover

這兩種模式影響視錐的形狀和大小 以及相機看到的場景畫面

later in this lesson.

在透視模式下相機如同真實世界的相機 有遞減透視的感覺

We can have any number of cameras in our scene.

可以看到場景裡代表視野的白色視錐 距離相機越遠越大

Each rendering different parts of the environment.

這是普遍製作遊戲用的模式

In this example we have three cameras.

正射模式不會有遞減透視的感覺

One rendering all of the dynamic

所有的物件都是使用 平行投影的方式來呈現

objects in the scene. Another rendering

可以看到場景的視錐是前後一樣寬的長方體

the static background and a third

這個模式通常使用在等距(Isometric)

rendering a User Interface overlay.

像是即時戰略、桌遊或2D遊戲、益智遊戲 或製作遊戲的小地圖或抬頭顯示器介面

All three cameras can be brought together to

要控制場景顯示多少內容 可調整Near和Far屬性改變視錐的形狀大小

make a single presentation to our user.

視野(Field of View)和真實相機的Zoom很像 用來控制相機視野有多廣

We will talk about how to properly use all

當相機使用正射模式時 屬性檢視的Field of View會變成Size

three cameras at once later on in this lesson.

用來控制可視區域的大小

When a camera is selected in the hierarchy

它和視野很像

we see a preview of the camera in the scene.

只是它會同時改變前後視切面的大小 因為正射相機沒有透視概念

When we have multiple cameras in the scene

我們的場景須要一個背景

this helps us to see what the camera is rendering.

可以用Clear Flags和Background來設定

This preview is also helpful when we are in

設定背景的顏色會影響 所有場景物件背後的顏色

full screen mode to see what the camera is rendering,

新建場景預設值是藍色

even if it's the only camera in the scene.

Clear Flags決定顯示背景的方式

Cameras will render everything that's in

這個設定在複數相機時特別重要

front of them and within their view.

每台相機在著色時會儲存顏色和深度資料 如果畫面被認為是空的就不會被呈現出來

How much of the scene is within their view

而Clear Flags屬性決定呈現在背後的是甚麼

is shown in the scene view as a white outline.

如果我們設定一個天空盒(Skybox) 背景就會變成天空盒

This shape is a view frustum.

天空盒是相機預設的選項

A view frustum is a pyramid, or cone,

天空盒是材質的一種，提供場景 一個紋理背景包含環繞場景的圖

with the top cut off.

更多天空盒的細節和使用方式 請參閱相關章節

The cut off top of the pyramid is the

如果我們不是選Skybox或是選了Solid color

near clipping plane and the base

所有物件的背景就會呈現指定的顏色

is the far clipping plane.

Depth Only主要用在多個相機的配合 等一下我們會討論

The near and far clipping planes control

Don't Clear產生的新畫面會蓋在舊畫面上 而製造出一種殘影效果，這功能不太常用

the draw distance from the camera.

Depth only運用在多個相機是很實用的功能

Objects must be between the near and far

透過這個設定相機被賦予深度這個變數

clipping planes to be rendered. The sides

每個相機的內容會依照深度 從最小的開始往上疊

indicate how much the camera can see

通常主相機的深度視應該是最小 而且Clear flag應該是skybox或solid color

side to side and top to bottom.

其他的相機就設為Depth only

and any part of the scene that's within

這樣就有一個最後面的背景 然後其他相機的畫面層層疊在主相機之上

the frustum will be rendered.

相機呈現哪些物件 可以用剔除遮罩(Culling Mask)來限制

Cameras have two different ways of

剔除遮罩下拉選單會列出 場景內圖層(Layer)的清單

looking at the scene. Perspective mode

相機只會顯示有勾選的圖層項目

and orthographic mode.

更多關於圖層和使用方法請參閱相關章節

These dramatically effect the shape and

關於將使用者介面(UI)疊在畫面上的方法

size of the frustum and the

我們將UI物件指定到名為UI的圖層

look of the scene through the camera.

照著UI的相機在遮罩設定只顯示UI圖層

In perspective mode the camera will render

然後設定Clear flag為Depth only 並設定深度設定大於其他相機

the scene like a real world camera with

這樣這台相機將只顯示遮罩指定的UI物件 並依照深度設定顯示在畫面最上面

a sense of diminishing perspective.

還有就是設定相機為正射(Orthographic) 可避免產生UI元件的不需要的透視感

We can see this in the scene view as the

一般這種多相機會用在介面像是 小地圖、遊戲世界抬頭顯示器

white representation of the cameras

模擬後照鏡或遙控導彈的液晶螢幕 或用來強制物件顯示順序

frustum gets larger as it extends

例如讓FPS玩家手上的槍 不會插入到遊戲建築場景內

away from the camera.

其他關於可視區規格化、著色路徑 目標貼圖和高動態範圍(HDR)性能

This is the most common camera mode to use

和更多高階功能會在其他章節介紹

when creating a game.

In orthographic mode there is no

diminishing perspective. All objects are

rendered using a form of parallel

projection from the camera. We can see this

in the scene view as the frustum is straight

and the front and back are the same size.

This mode is usually seen in isometric

games like some real time strategy or

board games, or for 2D

games, simple puzzle games and when using

an additional camera for rendering UI elements

on top of the game view, like mini

maps or heads-up displays.

To control what is being rendered in our

scenes, adjust the near and far clipping

planes and the size or shape of the frustum.

Field Of View controls how wide the view

of the camera will be. This is very much

like using the zoom on a real world camera.

When the camera is in orthographic mode

size replaces the field of view property.

This controls the size of the

orthographic viewport.

This is similar to field of view but

the value of the size property changes

the size of both the front and back planes

at the same time as there is no perspective

with an orthographic camera.

Our scenes must have some sort of a background.

This controlled by the Clear Flags and

Background properties.

The colour values set in the background

property will be what's drawn behind any

of the objects in our scene, if no other

settings have been changed. This is the

default blue colour we see in a new empty scene.

Clear Flags determines what the background

will be for a camera. This setting is particularly

important when using multiple cameras.

Each camera stores colour and depth information

when it renders it's view. The portions of the

screen that are not drawn upon are considered empty.

The Clear Flags property will determine

what is shown in this empty space.

If we have a skybox set in our render

settings the background will be a skybox.

Skybox is the default clear flag for any camera.

A skybox is a material that contains

several images that surround the entire scene

providing a textured background for that scene.

For more information on skyboxes and

render settings see the appropriate lessons.

If we don't have a skybox set, or we choose

solid colour as our clear flag.

The colour value from the background property

will be used behind any of our objects

in the scene.

Depth Only is primarily used for

multiple cameras. We will cover depth only

in a moment.

Don't Clear will result in each frame

being drawn over the last, creating

a smear effect. This setting isn't typically

used in games.

When using multiple cameras the most practical

setting for clear flags is depth only.

With this setting each camera is given a

value and depth and the contents of each

camera's view are layered on top of each other

in depth order, starting with

lowest depth first.

Normally the main camera is assigned

the lowest depth value

and has it's clear flag set to either

skybox or solid colour.

All of the other cameras have their clear

flags set to depth only. This way there is

one ultimate background, and the images

of all the other cameras are

layered on top of the main camera.

The content of what the camera is rendering

is limited by the Culling Mask property.

The Culling Mask drop down will list

all the layers available in the scene.

The camera will render only those objects

on the layers selected in it's culling mask.

For more information on layers and how to

use then see the appropriate lesson.

In the case of the User Interface overlay

we have the interface element set to the

UI layer. Our UI camera has it's culling mask

set to render only the objects on the User Interface layer

We have our clear flag set to depth only

and the depth set to the highest value

of all the cameras in the scene.

This way the UI camera only draws

the UI element based on the culling mask

setting and the UI element draws on top

of all of the other layers, based on the depth.

It is also worth noting that the camera is set to

orthographic to remove any possible

perspective on the UI element.

Typical uses of multiple cameras

are to render UI elements like

mini maps or heads-up displays over the

world view, make rear-view mirrors and

missile cameras, or to force the drawing order

of objects in the scene, like making

sure that a gun in a first person shooter

doesn't get drawn inside the level geometry.

The normalised viewport rect, render path,

target texture and HDR properties

are more advanced and will be covered in an other lesson.